Layer 2 Gateway (L2GW)
draft-xia-nvo3-l2gw-00
Liang Xia, Lucy Yong
March 2014 London England
Background
• Present situation:
– NVO3 tech-based L2 overlay networks are
becoming more and more deployed in DC currently;
– Traditional L2 bridge network [IEEE 802.1Q] still
exists widely in DC for connecting non-virtualized
devices (e.g. physical servers, storage systems, etc);
• Problem: How to interconnect L2 overlay
network with L2 bridge network?
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L2GW Solution
• L2GW (Layer 2 Gateway) -- gateway functions
to interconnect an L2 overlay network with an
L2 bridge network:
– Encapsulation translation between 2 networks;
– Deals with Layer 2 Control Protocol (L2CP) frames
between 2 networks—specified in this draft
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What is L2CP?
• L2CP (Layer 2 Control Protocol) -- defined by
IEEE802.1 to be used for L2 network control,
e.g., STP, LACP, etc. An L2CP is identified by
one of the following MAC destination
addresses:
– 01-80-C2-00-00-00 through 01-80-C2-00-00-0F:
Bridge Block of protocols
– 01-80-C2-00-00-20 through 01-80-C2-00-00-2F:
GARP/MRP Block of protocols
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L2CP process in L2 bridge network
specified by IEEE 802.1
Table part--2
Table part--1
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Analysis of L2CP process in L2 overlay
network
• L2CP in L2 overlay network: most of L2CPs are
unnecessary in L2 overlay network because it
has its own control plane functions to support
needed L2 communication such as transport
over a tunnel or OAM;
• And, it is very useful to document how these
service frames should be handled at L2GW to
ensure that two networks can interwork.
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Detailed analysis of L2CP process in L2
overlay network
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Detailed analysis of L2CP handling
across L2GW
• L2CP Frames Filtered (Peered or Discarded) in
L2GW: xSTP, LACP/LAMP(01-80-C2-00-00-02),
PAUSE, E-LMI, LLDP, PTP Peer Delay;
• L2CP Frames Passed through L2GW:
LACP/LAMP(01-80-C2-00-00-00), GARP/MRP
series protocols (i.e., MMRP, MVRP);
• TBD: Link OAM, …
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Next Step
• Comments and suggestions?
• Need feedbacks from IEEE!
• Other Interworking Cases:
– L2 bridge network: Provider Bridge [IEEE802.1AD],
Backbone Bridge [PBB] [IEEE802.1AH];
– L2 overlay network: VPLS [RFC4761] [RFC4762], EVPN
[EVPN], Shortest Path Bridging [IEEE SPB] and TRILL
[RFC6325]
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Thanks!
Liang Xia
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